/*
 * SM4 implementation
 * GM/T 0002-2012 Chinese National Standard ref:http://www.oscca.gov.cn/ 
 */

#include <stdio.h>
#include <stdlib.h>
#include "sm4.h"


/* Implementation that should never be optimized out by the compiler */
static void zeroize( void *v, unsigned int n ) 
{
    volatile unsigned char *p = (unsigned char *)v; while( n-- ) *p++ = 0;
}

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_UINT32_BE
#define GET_UINT32_BE(n,b,i)                             \
{                                                       \
    (n) = ( (unsigned int) (b)[(i)    ] << 24 )        \
        | ( (unsigned int) (b)[(i) + 1] << 16 )        \
        | ( (unsigned int) (b)[(i) + 2] <<  8 )        \
        | ( (unsigned int) (b)[(i) + 3]       );       \
}
#endif

#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n,b,i)                             \
{                                                       \
    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
}
#endif

/*
 *rotate shift left marco definition
 *
 */
#define  SHL(x,n) (((x) & 0xFFFFFFFF) << n)
#define ROTL(x,n) (SHL((x),n) | ((x) >> (32 - n)))

#define SWAP(a,b) { unsigned int t = a; a = b; b = t; t = 0; }

/*
 * Expanded SM4 S-boxes
 * Sbox table: 8bits input convert to 8 bits output*/
 
static const unsigned char SboxTable[16][16] = 
{
	{0xd6,0x90,0xe9,0xfe,0xcc,0xe1,0x3d,0xb7,0x16,0xb6,0x14,0xc2,0x28,0xfb,0x2c,0x05},
	{0x2b,0x67,0x9a,0x76,0x2a,0xbe,0x04,0xc3,0xaa,0x44,0x13,0x26,0x49,0x86,0x06,0x99},
	{0x9c,0x42,0x50,0xf4,0x91,0xef,0x98,0x7a,0x33,0x54,0x0b,0x43,0xed,0xcf,0xac,0x62},
	{0xe4,0xb3,0x1c,0xa9,0xc9,0x08,0xe8,0x95,0x80,0xdf,0x94,0xfa,0x75,0x8f,0x3f,0xa6},
	{0x47,0x07,0xa7,0xfc,0xf3,0x73,0x17,0xba,0x83,0x59,0x3c,0x19,0xe6,0x85,0x4f,0xa8},
	{0x68,0x6b,0x81,0xb2,0x71,0x64,0xda,0x8b,0xf8,0xeb,0x0f,0x4b,0x70,0x56,0x9d,0x35},
	{0x1e,0x24,0x0e,0x5e,0x63,0x58,0xd1,0xa2,0x25,0x22,0x7c,0x3b,0x01,0x21,0x78,0x87},
	{0xd4,0x00,0x46,0x57,0x9f,0xd3,0x27,0x52,0x4c,0x36,0x02,0xe7,0xa0,0xc4,0xc8,0x9e},
	{0xea,0xbf,0x8a,0xd2,0x40,0xc7,0x38,0xb5,0xa3,0xf7,0xf2,0xce,0xf9,0x61,0x15,0xa1},
	{0xe0,0xae,0x5d,0xa4,0x9b,0x34,0x1a,0x55,0xad,0x93,0x32,0x30,0xf5,0x8c,0xb1,0xe3},
	{0x1d,0xf6,0xe2,0x2e,0x82,0x66,0xca,0x60,0xc0,0x29,0x23,0xab,0x0d,0x53,0x4e,0x6f},
	{0xd5,0xdb,0x37,0x45,0xde,0xfd,0x8e,0x2f,0x03,0xff,0x6a,0x72,0x6d,0x6c,0x5b,0x51},
	{0x8d,0x1b,0xaf,0x92,0xbb,0xdd,0xbc,0x7f,0x11,0xd9,0x5c,0x41,0x1f,0x10,0x5a,0xd8},
	{0x0a,0xc1,0x31,0x88,0xa5,0xcd,0x7b,0xbd,0x2d,0x74,0xd0,0x12,0xb8,0xe5,0xb4,0xb0},
	{0x89,0x69,0x97,0x4a,0x0c,0x96,0x77,0x7e,0x65,0xb9,0xf1,0x09,0xc5,0x6e,0xc6,0x84},
	{0x18,0xf0,0x7d,0xec,0x3a,0xdc,0x4d,0x20,0x79,0xee,0x5f,0x3e,0xd7,0xcb,0x39,0x48}
};

/* System parameter */
static const unsigned int FK[4] = {0xa3b1bac6,0x56aa3350,0x677d9197,0xb27022dc};

/* fixed parameter */
static const unsigned int CK[32] =
{
	0x00070e15,0x1c232a31,0x383f464d,0x545b6269,
	0x70777e85,0x8c939aa1,0xa8afb6bd,0xc4cbd2d9,
	0xe0e7eef5,0xfc030a11,0x181f262d,0x343b4249,
	0x50575e65,0x6c737a81,0x888f969d,0xa4abb2b9,
	0xc0c7ced5,0xdce3eaf1,0xf8ff060d,0x141b2229,
	0x30373e45,0x4c535a61,0x686f767d,0x848b9299,
	0xa0a7aeb5,0xbcc3cad1,0xd8dfe6ed,0xf4fb0209,
	0x10171e25,0x2c333a41,0x484f565d,0x646b7279
};


/*
 * private function:
 * look up in SboxTable and get the related value.
 * args:    [in] inch: 0x00~0xFF (8 bits unsigned value).
 */
static unsigned char sm4Sbox(unsigned char inch)
{
    unsigned char *pTable = (unsigned char *)SboxTable;
    unsigned char retVal = (unsigned char)(pTable[inch]);
    return retVal;
}

/*
 * private F(Lt) function:
 * "T algorithm" == "L algorithm" + "t algorithm".
 * args:    [in] a: a is a 32 bits unsigned value;
 * return: c: c is calculated with line algorithm "L" and nonline algorithm "t"
 */
static unsigned int sm4Lt(unsigned int ka)
{
    unsigned int bb = 0;
    unsigned int c = 0;
    unsigned char a[4];
	unsigned char b[4];
    PUT_UINT32_BE(ka,a,0)
    b[0] = sm4Sbox(a[0]);
    b[1] = sm4Sbox(a[1]);
    b[2] = sm4Sbox(a[2]);
    b[3] = sm4Sbox(a[3]);
	GET_UINT32_BE(bb,b,0)
    c =bb^(ROTL(bb, 2))^(ROTL(bb, 10))^(ROTL(bb, 18))^(ROTL(bb, 24));
    return c;
}

/*
 * private F function:
 * Calculating and getting encryption/decryption contents.
 * args:    [in] x0: original contents;
 * args:    [in] x1: original contents;
 * args:    [in] x2: original contents;
 * args:    [in] x3: original contents;
 * args:    [in] rk: encryption/decryption key;
 * return the contents of encryption/decryption contents.
 */
static unsigned int sm4F(unsigned int x0, unsigned int x1, unsigned int x2, unsigned int x3, unsigned int rk)
{
    return (x0^sm4Lt(x1^x2^x3^rk));
}


/* private function:
 * Calculating round encryption key.
 * args:    [in] a: a is a 32 bits unsigned value;
 * return: sk[i]: i{0,1,2,3,...31}.
 */
static unsigned int sm4CalciRK(unsigned int ka)
{
    unsigned int bb = 0;
    unsigned int rk = 0;
    unsigned char a[4];
    unsigned char b[4];
    PUT_UINT32_BE(ka,a,0)
    b[0] = sm4Sbox(a[0]);
    b[1] = sm4Sbox(a[1]);
    b[2] = sm4Sbox(a[2]);
    b[3] = sm4Sbox(a[3]);
	GET_UINT32_BE(bb,b,0)
    rk = bb^(ROTL(bb, 13))^(ROTL(bb, 23));
    return rk;
}

static void sm4_setkey( unsigned int SK[32], unsigned char key[16] )
{
    unsigned int MK[4];
    unsigned int k[36];
    unsigned int i = 0;

    GET_UINT32_BE( MK[0], key, 0 );
    GET_UINT32_BE( MK[1], key, 4 );
    GET_UINT32_BE( MK[2], key, 8 );
    GET_UINT32_BE( MK[3], key, 12 );
    k[0] = MK[0]^FK[0];
    k[1] = MK[1]^FK[1];
    k[2] = MK[2]^FK[2];
    k[3] = MK[3]^FK[3];
    for(; i<32; i++)
    {
        k[i+4] = k[i] ^ (sm4CalciRK(k[i+1]^k[i+2]^k[i+3]^CK[i]));
        SK[i] = k[i+4];
	}

}

/*
 * SM4 standard one round processing
 *
 */
static void sm4_one_round( unsigned int sk[32],
                    unsigned char input[16],
                    unsigned char output[16] )
{
    unsigned int i = 0;
    unsigned int ulbuf[36];

    memset(ulbuf, 0, sizeof(ulbuf));
    GET_UINT32_BE( ulbuf[0], input, 0 )
    GET_UINT32_BE( ulbuf[1], input, 4 )
    GET_UINT32_BE( ulbuf[2], input, 8 )
    GET_UINT32_BE( ulbuf[3], input, 12 )

    while(i<32)
    {
        ulbuf[i+4] = sm4F(ulbuf[i], ulbuf[i+1], ulbuf[i+2], ulbuf[i+3], sk[i]);
	    i++;
    }

	PUT_UINT32_BE(ulbuf[35],output,0);
	PUT_UINT32_BE(ulbuf[34],output,4);
	PUT_UINT32_BE(ulbuf[33],output,8);
	PUT_UINT32_BE(ulbuf[32],output,12);
}

void sm4_init( sm4_context *ctx )
{
    memset( ctx, 0, sizeof( sm4_context ) );
}

void sm4_free( sm4_context *ctx )
{
    if( ctx == NULL )
        return;
	
    zeroize( ctx, sizeof( sm4_context ) );
}

/*
 * SM4 key schedule (128-bit, encryption)
 */
void sm4_setkey_enc( sm4_context *ctx, unsigned char key[16] )
{
    ctx->mode = SM4_ENCRYPT;
	sm4_setkey( ctx->sk, key );
}

/*
 * SM4 key schedule (128-bit, decryption)
 */
void sm4_setkey_dec( sm4_context *ctx, unsigned char key[16] )
{
    int i;
	ctx->mode = SM4_DECRYPT;
    sm4_setkey( ctx->sk, key );
    for( i = 0; i < 16; i ++ )
    {
        SWAP( ctx->sk[ i ], ctx->sk[ 31-i] );
    }
}


/*
 * SM4-ECB block encryption/decryption
 */

int sm4_crypt_ecb( sm4_context *ctx,
				   int mode,
				   int length,
				   unsigned char *input,
                   unsigned char *output)
{
    while( length > 0 )
    {
        sm4_one_round( ctx->sk, input, output );
        input  += 16;
        output += 16;
        length -= 16;
    }

	return( 0 );
}

/*
 * SM4-CBC buffer encryption/decryption
 */
int sm4_crypt_cbc( sm4_context *ctx,
                    int mode,
                    int length,
                    unsigned char iv[16],
                    unsigned char *input,
                    unsigned char *output )
{
    int i;
    unsigned char temp[16];
	unsigned char *pbIV = NULL;
	
	pbIV = (unsigned char *)malloc(16);
	memcpy(pbIV, iv, 16);

    if( mode == SM4_ENCRYPT )
    {
        while( length > 0 )
        {
            for( i = 0; i < 16; i++ )
                output[i] = (unsigned char)( input[i] ^ pbIV[i] );

            sm4_one_round( ctx->sk, output, output );
            memcpy( pbIV, output, 16 );

            input  += 16;
            output += 16;
            length -= 16;
        }
    }
    else /* SM4_DECRYPT */
    {
        while( length > 0 )
        {
            memcpy( temp, input, 16 );
            sm4_one_round( ctx->sk, input, output );

            for( i = 0; i < 16; i++ )
                output[i] = (unsigned char)( output[i] ^ pbIV[i] );

            memcpy( pbIV, temp, 16 );

            input  += 16;
            output += 16;
            length -= 16;
        }
    }

	free(pbIV);
	pbIV = NULL;
	return( 0 );
}
